A descaling target with a deposit of scales is to be coated with a solvent at least on the scaled side.
A coil is supplied with a signal of a frequency preset for every scale as a frequency signal.
If the off period is smaller than the on period, an indication is given that there is scale deposit in the water pipe (6).
The preset frequency of the frequency signal to be supplied to the coil is a frequency as current flows through the solvent which coats the scale in the magnetic field formed by the supply of the frequency signal to the coil.
These dish-washing detergents containing amino acids show markedly better properties of inhibiting calcium buildup than conventional dish-washing detergents based on carbonate and/or hydrocarbonate.